Variable speed power drive



July 23, 1940. G. c. JETT VARIABLE SPEED POWER DRIVE Filed Nov. l, 1939 2 Sheets-Sheet l INVENTOR. eoge C Je@ ATTORNEY.

July 23, 1940.

G. C. JETT VARIABLE SPEED PUWER DRIVE Filed No'v. 1, 1939 2 Sheets-Sheet 2 INVENTOR. 08059@ C J ATT NFY.

Patented July 23, 1940 l 2,209,023 VARIABLE sPEEnPoWER univr:

George O. Jett, Milwaukee, Wis. `Application November 1, 1939, SeriaLNo. 302,301

i is claims. (o1.` 'r4- 284) 1` This invention `relates `in `general `to power :transmission mechanisms and more particularly to that type adapted to converta constant speed input into an infinitely variable speed output, the mechanism being capable of manual adjustment throughout the entire range of an infinitely variable speed cycle, and while oontinuousli7 transmitting power. The present application is a continuation in partof application Serial No.

'150,272, filed June 25, 1937.

I am aware that variable speed transmitting mechanisms comprising a pair of oppositely disposed frustro-conical rollers or pulleys connected fore been employed, but due to the difliculty `of controlling the belt because of its tendency to creep toward the largerends of the pulleys, such transmission mechanisms are not considered very practical and are not generally used for. the transmission of heavy power..-0ne of the purposes of my present invention is to provide a lvariable speed power drive which-is capable of use for heavy duty purposeswhich iscompact in arrangement so as to occupy a: minimum of space, which can be readily andeasily adjusted for speed variation purposes while in operation, which is capable of maintaining the power` output shaft at Yzero revolutions while ,under load and with the power input shaft continuously driven at a constant speed, and which will be durable and reliable in operation and capable of being economically produced. i t i With these ends in view, my Vinvention `contemplates the `provision of a mechanism comprising a plurality of frustro-conical drivingV rolls or pulleys and a corresponding plurality of driven frustro-conical rolls or pulleys in conjunction with a circular driving element encircling and embracing al1 of the drivingl and driven rolls so as to frictionally engage :the rolls and transmit without appreciable slippage or loss of power the rotative movement of the driving rolls to the driven rolls. 'Ilie encircling driving :element is carried by a rigid ring or rim which is freely `element is at all times under complete control se that .all tendency tu Whiprineis Qhifiated and by a shiftable beltthroughwhich power is trans- Y, lmitted from one pulley to the other have heretoany` creeping` tendency is effectively counteracted without the imposition of destructive `,strains upon the element.

Another `feature of my invention resides the structure of thedriving element itself which, instead of being a flat belt, is construotedin the form of a pneumatic tire or tube mounted at its 'outer perimeter within an annular rim and having the `tread formed upon its inner perimeter for frictional driving engagement with the driving anddriven rolls encircled by the pneumatic driving element. In this novel type of power transmitting drive, the power transmitted without slippage or loss is dependent upon three factors,

namely, the degree of pressure between the surrounding pneumatic driving element and the encircled driving ,and drivenfrolls, the contact area between each roll and the driving element, which is determinedby the extent of the depression of the rolls into the surface of the driving element;

and the ,character of the engaging surfaces of the `rolls and the driving element. In accordance with my invention, the pressure factor is dependent upon the amount of air pressure within the pneumatic `driving element. The contact area between each roll and the driving element isdependent upon the settingof the roll with respect 'tot the driving element, and the effective frictional engagement between the rolls and the driving element is raised to the maximum by sturdy and compact arrangement which occupies Y,

Va minimum of space is attained.

Other purposes and advantageous features of my invention will be appreciated as the same becomes better understood by reference to the following description when considered in connection with the accompanying drawings,

Referring to the drawings,

Fis- 1 is aloneitudinal sectional View through a power transmitting device embodying my invention; Fis. 2 is a sectional view on the `line 2-2 of Fig. 1; i

Fig, '3 is a fragmentary somewhat diafainmatic and \ corrugating or otherwise roughening the surfaces Fig. Llis a sectional view on the line 4--4 of Fig. 2.

Referring to the drawings more in detail, it will be observed that the power transmitting mechanism comprises a plurality of, in the present instance two, driving rolls or pulleys and an equal number of driven rolls or pulleys 6. The driving and driven rolls are arranged in alternation about a common center or axis from which the most remotetppints of-all the rolls are equally spaced. The rollsj are all frustro-conical inform, the driving rolls being positioned with theirvlarger ends uppermost, and the driven rolls being positioned with their smaller ends uppermost. The axes of the rolls are inclined, as will be apparentfrom Figs. 1 and 2, so that the longitudinal line includ-l ed in the perimeter of each roll which is mostremote from said commonaxisiis `parallel therewith, equi-distant from the axis, and parallel with the corresponding lines of all the`other rolls. The'shafts-projecting 'from the lower'ends of the cdrivin-grolls 'are journalled in suitable bearings 1 carried by an inverted dished frame plate 8 secured at its perimeter by bolts 9 to the flange I I -offthe base or standard LIZ upon which the mech- 'anism is mounted. f

A standard I3l rising centrally from the plate 8 carries at its upper end a head I4 shaped as shown in Fig. 1 to provide supports for the cen- 'tering studs I51of the driving rolls and the similar studs I6 of the driven rolls.l The upper ends of 4the-` drivingrolls `are rotatably mounted on the 'studslI" through the intermediary'of the ball bearings I1, and the driven rolls are similarly mounted on studs I6 through the intermediaryof the balllbearings` I3. Bolts I9-secure the head I4 tothe' upper end of the standard I3; The studs -ESand- I6 are threaded through and longitudinally'. adjustable with respectto the head I4 to thereby 'afford facility for longitudinal adjustment "of theposition ofthe driving and driven rolls 'whereby theradialdistance from the axis, about which the rolls Aare grouped,.to the most remote point of-each rollerlmay be regulated' for purposes which will be laterexplained.

The transversely extending wall 20 of the base l2 isprovided withacentralbearingZI in which Aisljournalled `a sleeve shaft 22 ycarrying below the ffbearing a sprocket wheel=23 ora gear or a pulley "..which `constitutes the power input element of the n1echanism. `The sprocketillustrated inthis instance is adapted to be driven by a chain 24 which in turn is driven `at a constant speed from any A'suitable source ofv power. a y A large, .slightly beveledgear 25 is fixed upon Vthesleeve or hollow shaft 22 above bearing 2I and lis .drivingly meshed with the beveled pinions ,26 fixed upon thedrive roll shafts projecting through -gbearings 1. Suitable packing 21 surrounds these shafts to. precludeoil leakage between the chamber included between plate, 8 and wall 26 and the V ,hambersurrounding the driving rolls 5 and 6. ,.'lhel-,hubof gear `25 is .extended upwardly and 0,forms a continuation of sleeve `22 in which is Vjournalled a shaft Zlcarrying'at its upper end andnternal gear 2.9, the upper end" of the shaft above the gear being rf'ntatablyV guided in bearings .3 ldcarried bythe inverted vplate 8.' Shaft 28 con- 'stituts the 'power outputshaft of the mechanism. A be'veled'gear'l-BZ journalledupon the upstanding hub carries a plurality of A(in the present in- "Vtnenub'jabqv-the gear' 3,2.

The-l lower lend" 'of eachdriveni rollt-shaft 35 hicle tires.

carries, as best shown in Fig. 2, a pinion 36 meshing with the beveled gear 32, whereby a driving connection is established between the driving rolls 5 and the driven rolls 6 through the. planetary transmission carried by the hollow shaft 22. This planetary connection serves not to drive one set of rolls from the other, but as a synchronizing mechanism through which the speed of the power output shaft 28 is regulated and controlled.

Driven rolls 6 are driven from the driving rolls 5 through the intermediary of a circular, flexible pneumatic driving element"frictionally engaging a segment of the perimeter of each of the driving and driven rolls. While the driving element may be made of any suitable material possessing the desired characteristics, it is here illustrated as being in the form of a pneumatic tire or tube 31 having the tread or driving face upon the inner perimeter of the tube instead of upon the outer` perimeter, as is customary with pneumatic ve- This driving element is mounted in a surrounding rim or carrier 38 'ofsubstantial and rigid construction which is rotatably supported by the arms 39 of an open frame which in turn is rotatably carried by a ball bearing assembly 4I mounted on a sleeve 42 which is slidable longitudinally of a guide tube 43 anchored at its lower end by a bolt 44 in the head I4. This tube is longitudinally slotted at one side, as indicated at 45, to accommodate a segmental nut 46 fixed to the sleeve 42, which nut threadedly engages a screw threaded rod 41 housed within the tube d'3. To the upper end of this rod there is removably attached a hand wheel 48 by which the rod may be rotated to raise and lower the open frame through the intermediary of` the segmental nut 46.

To enable the removal of the casing 49 surrounding the group of rolls, the driving element and its supporting frame, a sleeve 5I is fixed therein and provided with a tapered socket to receive the upper end of tube 43, and between this sleeve and the inner walls of the hub of the hand wheel, a ball bearing assembly 52 is interposed.

In Figs. 1 and 2, the driving element 31 is shown instance, when the driving element is in its uppermost position engaging the rolls 5 at their largest diameters and the driven rolls 6 at their smallest diameters, the driving element will be caused to revolve around the Arolls at maximum speed, thereby driving the driven rolls at maximum speed. At the other extreme position of the driving element illustrated in dotted lines in Fig. 2, the driving element, since it engages the driving rolls at their `smallest diameter, will be driven at minimum speed, and since it at the same time engages the driven rolls on their greatest diameter, these rolls will be in turn driven at minimum speed. It will be apparent, therefore,

` that with the driving rolls rotated at a constant speed, a wide Varia-tion in the speed of rotation of the beveled gear 32 driven by the driven rolls. 6 may be attained by adjusting the driving element 31 to infinitely variable positions within the limits of its adjustability.

To assure adequate driving friction between the -Atread-of the drivingelement 31 and the driving and driven rolls 5 and G embraced thereby and to `insure against slippage and loss of power in the driving, the surfaces of both the driving `and driven rolls are roughened, preferably by pro-` viding them with small longitudinally extending corrugations, as illustrated on the drawings, particularly in Fig, 3. This gure also illustrates the depression of the driving and driven rolls into the flexible driving element 31 so as to enlarge the areaof Contact between the rolls and the element and to, in effect, cause `the element to be partally wrapped around the rolls. rThis wrapping action and increase in contact area manifestly increases the tractive or driving friction between the element of the rolls and correspondingly reduces the liability of slippage. As previously mentioned, the pressure between the rolls and the driving element may also be regulated by adjustment of the rolls which, in effect, decreases or diminishes their spread, `and further` provision for pressure regulation is afforded by the driving element itself within which the air pressure may be increased or diminished as occasion requires in a manner commonly employed in connection with automobile tires. The driving element provided with a valve equipped nipple through which the air pressure within the` driving element may be increased or diminished as desired ends, as indicated by 51.

In some uses of a transmission of this type, the load at certain speeds may be very light Consequently, for conservation of energy and reduction in wear, it may be desirable to relieve to some extent the driving pressure between the rolls and the driving element 31. To accomplish this result, the diameter of the driving and driven rolls may be slightly diminished at such point or points in their length as Will correspond with such light load speeds as determined by the position of adjustment of driving element 31. For instance, the driving rolls illustrated are shown as relieved or slightly reduced in diameter throughout an area indicated by reference character 5i and again near their smaller ends, as indicated by 55. Correspondinglv the driven rolls are reduced or relieved at 56 and also at their larger Such relief of pressure reduces the friction on the roll bearings and reduces the expenditure of energy required in depressing the driving element. At such points of pressure relief, the driving element will contact the driving and driven rolls with suiiicient pressure to drive them under light load conditions and, when adjusted to other speeds for heavy load conditions, `the normal driving pressure between the rolls and the driving element will be resumed. v

The mechanism illustrated and described may be mounted in any desired position, but is here shown as being vertically disposed. This position is preferably where a rubber driving element 31 is employed which must be kept free from contact with oil,\as in this instance the planetary and all of the driving gears are housed in a charm ber beneath the rolls where they may run in an `oil bath or oil spray, without danger of oil leakage, upwardly into the rolls or the driving the/driven rolls 5, which through the pinions 36 drive the beveled gear carrier 32 carrying the planet pinions `33 meshing with the sun pinion 34 xed-onshaft 22 and also with the internal gear 23. -iixed upon the upper end of power output shaft 28. i f i The `beveled `gear 32 constitutes a spider for a planetary mechanism comprisingthe planet pinions 33, sun ipinion34, and internal gear 29,4 all oflwhich revolve about the driven outlet shaft 28. The sun pinion 34 constitutes one of the driving members and being driven at a constant speed tends ltodrive the internal gear 29 at a reduced constant speed in the opposite direction.A The spider or gear `32 constitutes `the other driving member which tends to drive the internal gear 29-in the same direction as that of the sun pinion .34 but many `times faster than the sun gear when the driving element 31v is in` its top speed or uppermostxadjusted position.

Downward adjustment ofthe driving element 31 Will decrease the speed of `internal gear until when in its `lowest position, as shown in dotted lines on Fig. 2, the speed of spider gear 32 carrying planetpinions 33 bears such relation to `the speed of the' sun gear 34 that the driving effects of these gears upon internal gear 29 are exactly neutralized, and the planet pinions there- -upon revolve and rotate within the internal gear which remains stationary. The shaft 23 is under these conditions held stationary while under its full torque load. Otheradjusted positions of the driving element 31 will cause the shaft to be rotated atfinnitely variable speeds depending upon the adjusted position of the driving element.

yIt is believed that my invention and many of its inherent advantages should be appreciated from the foregoing as also the fact that the structural details illustrated and described may be varied within considerable limits without exceedfollowing claims.

I claim: ",1. yIn a variable speed power transmitting mechanism, 'the combination of a vplurality of ing Ithelscope ofthe invention as defined in the frustro-conical'driving rolls, a plurality of frustro-conical driven rolls arranged in alternation withsaid driving rolls about a common axis, the rolls being so arranged that the drivingrolls taper in the opposite` direction from the driven rolls and the outermost surfaces of all the rollsare disposed substantially parallel with said axis and thersame radial distance therefrom, means for rotating said driving rolls, a circular driving element surrounding and frictionally engaging all of said rolls for transmitting the rotation of the driving rolls to the driven rolls, means for maintaining the plane of said driving element pern pendicular to said axis, and means for adjusting said driving element longitudinally of said rolls to vary the speed of thedriven rolls relatively to that of the'driving rolls.

2. In a variable speed power transmission mechanism, the combination of a plurality of driving and `driven rolls arranged in alternation `about a common central airis, said rolls being parallel with and substantially equidistant from `said central axis,\a circular driving element surrounding and embracing all of the rolls, means `for adjusting `said `driving element longitudinally yso of the rolls, and means forrotating the driving rolls.

3. In a variable speed power transmission mechanism, the combination of a plurality of frustro-conical rolls arranged in a circle about a common central axis, alternate rolls being tapered in opposite directions and the outer faces of all the rolls being disposed in substantial parallelism with said axis, a circular driving element surrounding and frictionally engaging said outer faces of all the rolls, means for adjusting said driving element lengthwise of the rolls, means for driving the rolls of a group tapering in one direction, and means for transmitting power from the other group of rolls tapering in the oppo site direction.

4. In a variable speed power transmission mechanism, the combination of a plurality of frustro-conical driving rolls, a pluralityT of frustro-conical driven rolls arranged alternately with the driving rolls about a common central axis, the driving rolls tapering in one direction and the driven rolls tapering in the opposite direction and the most remote points on the surfaces of all the rolls being spaced equi-distant from said axis, the surfaces of all of said rolls being roughened, a circular driving element surrounding all of said rolls and frictionally contacting the roughened surfaces thereof, the roll contacting surface of said driving element being yieldable to increase the area of surface contact between said element and the rolls, and means for adjusting said element longitudinally of the rolls.

5. In a variable speed power transmission mechanism, the combination of a plurality of frustro-conical, longitudinally corrugated driving rolls, a plurality of frustro-conical longitudinally corrugated driven rolls, the driving rolls tapering in the opposite direction from the driven rolls and all of the rolls being grouped around a common central axis so as to present the outermost points on their surfaces at substantially equal radial distances from said axis, Ia pneu- `matic tubular driving element surrounding said group of rolls and provided on its inner periphery with a friction tread frictionally engaging all cf said rolls, said tread being yieldable to increase the area of contact between the tread and the rolls, means for supporting said driving element with the diameter thereof disposed in a plane perpendicular to said axis, and means for adjusting the position of said driving element longitudinally of the rolls.

6. In a variable speed power transmitting mechanism, the combination of a group of rolls of frustro-conical form arranged about a common central axis with the taper of adjacent rolls extending in the opposite direction and withthe axes of all the rolls inclined toward and intersecting said common axis so as to present the outermost points on the surfaces of all the rolls at a substantially equal radial distance from said axis, a tubular air-iilled, resilient driving element surrounding said rolls and having an internal, yieldable tread frictionally engagingl each of the rolls, a rigid annular supporting member for said driving element, and means for adjusting said member longitudinally of the rolls.

7. In a variable speed power transmission mechanism, the combination of a plurality of frustro-conical driving rolls, a plurality of frustro-conical driven rolls arranged in alternation with. said driving rolls about a common central axis, the driving and .driven rolls being tapered in opposite directions and positioned to dispose the outermost points of their surfaces substantially equi-distant from said axis, an annular tubular driving element provided with a yieldable internal tread frictionally engaging said outermost surface points of said rolls, and means whereby said rolls may be adjusted to regulate the pressure between said rolls and said driving element.

8. In a variable speed power transmission mechanism, the combination of a plurality of frustro-conical driving rolls, a plurality of frustro-conical driven rolls arranged in alternation with said driving rolls about a common central axis, the driving and driven rolls being tapered in opposite directions and positioned to dispose the outermost points on their surfaces substantially equi-distant from said axis, an annular tubular driving element provided with a yieldable internal tread frictionally engaging said outermost surface points of said rolls, and means whereby the resiliency of said driving element may be varied to regulate the pressure between said driving element and said rolls.

9. In a variable speed power transmission mechanism, the combination of a plurality of frustro-conical driving rolls, a plurality of frustro-conical driven rolls arranged in alternation with said driving rolls about a common central axis, the driving and driven rolls being tapered in opposite directions and positioned to dispose the surface points thereof most remote from said axis substantially equi-distant from said axis, an annular tubular driving element provided with a yielclable internal tread frictionally engaging vsaid outermost surface points of said rolls, means whereby said rolls may be adjusted to regulate the pressure between said rolls and said driving element, and means whereby the resiliency of said driving element may be varied to regulate the pressure between said driving element and said rolls.

10. In a variable speed power transmission mechanism, the combination of a series of frustro-conical rolls grouped in a circle about a common central axis with the rolls alternately tapering in opposite directions and so positioned that the outer longitudinally extending face lines of all the rolls are substantially equi-distant from said axis, an annular pneumatic driving element provided with an internal friction face surrounding and frictionally engaging all of said rolls, and means for adjusting said driving element longitudinally of the rolls, one or more of said rolls being of slightly reduced diameter at a predetermined point between its ends to relieve the pressure against said driving element at a predetermined driving speed.

1l. In a variable speed power transmission mechanism, the combination of a plurality of frustro-conical driving rolls, a plurality of frustro-conical driven rolls, the taper of the driving rolls extending in the opposite direction from that of the driven rolls and said driving and driven rolls being arranged in alternation about a common central axis, means for rotating the 'driving rolls at a common speed, and power transmitting mechanism positioned concentrically with said axis and within a circle including the shafts of said rolls and connected to receive power delivered by said driven rolls.

l2. In a variable speed power transmission mechanism, the combination oi' an upwardly crowned supporting member, a plurality of frustro-conical driving rolls journalled at one end in said member, a plurality of frustro-conical driven rolls journalled at one end in said member, said driving and driven rolls being tapered in opposite directions and arranged in` alternation about a common central axis with the outermost portion of all the rolls substantially equi-distant from said axis, means for driving the driving rolls at a common speed, an annular driving element for transmitting the rotation of the driving rolls to the driven rolls, means for adjusting said element longitudinally of the rolls to vary the speed between the driving and driven rolls, a

power transmitting unit positioned beneath the crown portion of said member coaxially with said axis and between the ends o1' the roll shafts, and a driving connection between said driven rolls and said unit.

13. In a variable speed power transmission mechanism, the combination of a power input shaft, a plurality of frustro-conical driving rolls, a driving connection between said shaft and said rolls, a plurality of frustro-conical driven rolls,

said driving and driven rolls being arranged in alternation about a common central axis with the driving and driven rolls tapering in opposite directions, a driving element surrounding and frictionally engaging all of said rolls, a power output shaft coaxial with said axis, a power transmission unit encircled by the shafts of said rolls and comprising a sun gear driven by the power input shaft, an internal gear connected with said power output shaft, a spider gear connected with said driven rolls and planetary pinions carried by said spider gear and meshing with said sun gear and with said internal gear, and means for adjusting said driving element longitudinally of the rolls to vary the speed between said driving and driven rolls so that said power output shaft niay be maintained motionless under full torque load while the power input shaft is continuously driven.

GEORGE C. JETT. 

